Taiwanese researchers take aim at environmental issues

TAIPEI--Taiwan's bulwark research centers are aiming to move the island nation up the supply chain from manufacturing to innovation by fostering cooperative industry/academic efforts to commercialize home-grown microelectronics, here aiming to solving environmental issues such as eliminating the negative environmental impact of rare-earth strip-mining and solving the mystery of disappearing honey bees.

To mitigate the need for the environmentally damaging strip mining practices used on the Chinese mainland to harvest rare earth minerals, IEEE Fellow Ching-Fuh Lin at National Taiwan University (NTU) has created nano-particle materials that are cheaper, more convenient to use, and easier to color balance than using the rare-earths required by solid-state lighting (SSL) today.

"We are merging light and electricity by designing environmentally friendly zinc-oxide alloys, with particle sizes in the 10s of nanometer range, that perform surface emission of light, making them a viable candidate for replacing the rare earths used today," said Lin, who is director of the Innovative Photonics Advanced Research Center (iPARC).

SSL today depends of rare-earth phosphors that glow throughout their bulk. But by switching to surface emission, ultra-thin coatings of zinc-oxide-based nano-particles can instead coat the inside of ultra-violet LEDs. By adjusting the size and alloy formulation of the film's nano-particles, Lin has produced a wide range of white-light color temperatures--from warm yellowish to cold bluish. Lin is now optimizing the process—now operating at 80 percent efficiency—which can be done at low temperatures and atmospheric pressures, in hopes of achieving 90 percent efficiency before commercialization.

Lin is also championing silicon foils as a substitute for the organic materials whose performance cannot match silicon. Funded by the National Science Council (Taiwan's version of the National Science Foundation), Lin has demonstrated the ability to create silicon substrates in the 5-to-15 micron range using a manufacturing process as cheap and benign as processing polymers, but with the high-performance of silicon.

"A single silicon wafer can be used to produce multiple silicon foils--by peeling off thin layers repeatedly," said Lin. "In this way our process could be as inexpensive as using organics [polymers], but the result is high-perforance single-crystal substrates."